// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_RENDERER_MOJO_CONTEXT_STATE_H_
#define CONTENT_RENDERER_MOJO_CONTEXT_STATE_H_

#include <memory>
#include <set>
#include <string>

#include "base/macros.h"
#include "base/memory/scoped_vector.h"
#include "gin/modules/module_registry_observer.h"
#include "v8/include/v8.h"

namespace blink {
class WebFrame;
class WebURLResponse;
}

namespace content {

class ResourceFetcher;
class MojoMainRunner;
enum class MojoBindingsType;

// MojoContextState manages the modules needed for mojo bindings. It does this
// by way of gin. Non-builtin modules are downloaded by way of ResourceFetchers.
class MojoContextState : public gin::ModuleRegistryObserver {
public:
    MojoContextState(blink::WebFrame* frame,
        v8::Local<v8::Context> context,
        MojoBindingsType bindings_type);
    ~MojoContextState() override;

    void Run();

    // Returns true if at least one module was added.
    bool module_added() const { return module_added_; }

private:
    class Loader;

    // Invokes FetchModule() for any modules that have not already been
    // downloaded.
    void FetchModules(const std::vector<std::string>& ids);

    // Creates a ResourceFetcher to download |module|.
    void FetchModule(const std::string& module);

    // Callback once a module has finished downloading. Passes data to |runner_|.
    void OnFetchModuleComplete(ResourceFetcher* fetcher,
        const std::string& id,
        const blink::WebURLResponse& response,
        const std::string& data);

    // gin::ModuleRegistryObserver overrides:
    void OnDidAddPendingModule(
        const std::string& id,
        const std::vector<std::string>& dependencies) override;

    // Frame script is executed in. Also used to download resources.
    blink::WebFrame* frame_;

    // See description above getter.
    bool module_added_;

    // Executes the script from gin.
    std::unique_ptr<MojoMainRunner> runner_;

    // Set of fetchers we're waiting on to download script.
    ScopedVector<ResourceFetcher> module_fetchers_;

    // Set of modules we've fetched script from.
    std::set<std::string> fetched_modules_;

    // The prefix to use for all module requests.
    const std::string module_prefix_;

    DISALLOW_COPY_AND_ASSIGN(MojoContextState);
};

} // namespace content

#endif // CONTENT_RENDERER_MOJO_CONTEXT_STATE_H_
